我已經開始使用一些基本思想進行編碼，并創建了一個名為 Student 的類來創建物件 hashmap 以執行插入和更新。下面顯示了一個名為 DatabaseHelper 的類來執行 SQLite 操作和主要活動。
Student.java 是一個類，其中包含諸如roll no、studentName、standard、course 和percent 等變數以及具有所有變數的引數化建構式。
package com.app.myapplication.Model;
import java.io.Serializable;
public class Student implements Serializable {
public String rollNo;
public String studentName;
public String standard;
public String course;
public String CGPA;
public Student(String rollNo, String studentName, String standard,String course, String CGPA) {
this.rollNo = rollNo;
this.studentName = studentName;
this.standard = standard;
this.course = course;
this.CGPA = CGPA;
}}
MainActivity.java
public class MainActivity extends AppCompatActivity {
private DatabaseHelper db;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
db= new DatabaseHelper(MainActivity.this);
HashMap<String,Student> map=new HashMap<String,Student>();
Student student1 = new Student("101","Linet","XII","Commerce","89%");
map.put("1",student1);
Boolean insert_student_details = db.InsertStudentDetails(map);
if(insert_student_details){
Log.v("Success msg","Student details insertion success");
}else{
Log.v("Failure msg","Student details insertion failed");
}
}
}
DatabaseHelper.java
public class DatabaseHelper extends SQLiteOpenHelper {
private static final int DATABASE_VERSION = 4;
SQLiteDatabase database;
String TBL_STUDENT = "tbl_student";
public DatabaseHelper(@Nullable Context context) {
super(context, "studentDb", null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase sqLiteDatabase) {
sqLiteDatabase.execSQL("CREATE TABLE IF NOT EXISTS " TBL_STUDENT "(id INTEGER PRIMARY KEY " " AUTOINCREMENT,rollNo TEXT,studentName TEXT,standard TEXT,course TEXT,subject TEXT,CGPA TEXT)");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " TBL_STUDENT);
onCreate(db);
}
public Boolean InsertStudentDetails(HashMap<String,Student> studentMap) {
long result = 0;
database = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
for(HashMap.Entry<String,Student> entry : studentMap.entrySet()) {
String key=entry.getKey();
Student student = entry.getValue();
contentValues.put(key, student.rollNo);
contentValues.put(key, student.studentName);
contentValues.put(key, student.standard);
contentValues.put(key, student.course);
contentValues.put(key, student.CGPA);
Log.v("msg", "rollNo:" student.rollNo);
Log.v("msg", "studentName:" student.studentName);
Log.v("msg", "standard:" student.standard);
Log.v("msg", "course:" student.course);
Log.v("msg", "CGPA:" student.CGPA);
result = database.insert("tbl_student", null, contentValues);
// result = database.insert(TBL_STUDENT,null, contentValues);
}
if (result == -1) {
Log.v("msg", "Failed");
//Remove_all_values_in_the_table_request();
return false;
} else {
Log.v("msg", "Success");
return true;
}
}
public boolean updateStudent(HashMap<String,Student> studentMap,String rollNo){
database = this.getReadableDatabase();
long res = 0;
Log.v("tbl_interval_timer", "rollNo " rollNo);
String query = "select * from " TBL_STUDENT " where rollNo ='" rollNo "'";
Cursor cursor = database.rawQuery(query, null);
int count = cursor.getCount();
if(count>0) {
Log.v("msg", "Data exist");
ContentValues contentValues = new ContentValues();
for(HashMap.Entry<String,Student> entry : studentMap.entrySet()) {
String key = entry.getKey();
Student student = entry.getValue();
contentValues.put(key, student.rollNo);
contentValues.put(key, student.studentName);
contentValues.put(key, student.standard);
contentValues.put(key, student.course);
contentValues.put(key, student.CGPA);
Log.v("msg", "rollNo:" student.rollNo);
Log.v("msg", "studentName:" student.studentName);
Log.v("msg", "standard:" student.standard);
Log.v("msg", "course:" student.course);
Log.v("msg", "CGPA:" student.CGPA);
res = database.update(TBL_STUDENT, contentValues, "rollNo = ? ",
new String[]{String.valueOf(rollNo)});
}
if (res == -1) {
Log.v("updateCyclicTimer msg", "Failed");
//Remove_all_values_in_the_table_request();
return false;
} else {
Log.v("updateCyclicTimer msg", "Success");
return true;
}
}else{
Log.v("updateCyclicTimer msg", "Data does not exist");
return false;
}
}
}
我收到如下所示的錯誤。
com.app.myapplication E/SQLiteLog: (1) near "1": syntax error in "UPDATE tbl_student SET 1=? WHERE rollNo = ?"
android.database.sqlite.SQLiteException: near "1": syntax error (code 1 SQLITE_ERROR): , while
compiling: UPDATE tbl_student SET 1=? WHERE rollNo = ?
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3449)
E/SQLiteLog: (1) near "1": syntax error in "INSERT INTO tbl_student(1) VALUES (?)"
E/SQLiteDatabase: Error inserting 1=89%
android.database.sqlite.SQLiteException: near "1": syntax error (code 1 SQLITE_ERROR): , while compiling: INSERT INTO tbl_student(1) VALUES (?)
如何解決這個問題？
uj5u.com熱心網友回復：
map.put("1",student1);
Boolean insert_student_details = db.InsertStudentDetails(map);
String key=entry.getKey(); // Is always 1
Student student = entry.getValue();
Student student = entry.getValue();
contentValues.put(key, student.rollNo);
contentValues.put(key, student.studentName);
contentValues.put(key, student.standard);
contentValues.put(key, student.course);
contentValues.put(key, student.CGPA);
向 contentValues 添加內容時，您需要輸入列名而不是鍵，因此您的 sql 陳述句看起來像這樣：insert into table_student(1,1,1,1,1) values (...)但它需要看起來像插入 table_student(rollNo,studentName,standard,course,CGPA) 值（...）
在您的更新和插入方法中以某種方式執行此操作：
map.put("1",student1);
Boolean insert_student_details = db.InsertStudentDetails(map);
String key=entry.getKey(); // Is always 1
Student student = entry.getValue();
Student student = entry.getValue();
contentValues.put('rollNo', student.rollNo);
contentValues.put('studentName', student.studentName);
contentValues.put('standard', student.standard);
contentValues.put('course', student.course);
contentValues.put('CGPA', student.CGPA);
我不知道你的列名，所以我假設它們是 rollNo、studentName、standard、course 和 CGPA。
我希望這有幫助 ;）
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